Circulatory System Of A Mammal

Question 1

Why do large organisms have specialist exchange surfaces?

Answer 1

-the surface area to volume ratio decreases so to a point where the organisms needs can no longer be met by the body surface alone

Question 2

what are the features of transport systems?

Answer 2

• a suitable medium in which to carry materials like blood which is normally based on water because water readily dissolves substances and can be moved around easily but can be a gas such as air breathed in and out of the lungs
• a form of mass transport in which the transport medium is moved around in bulk over large distances
• a closed system of tubular vessels that contains the transport medium and forms a branching network to distribute it to all parts of the organism
• a mechanism for moving the transport medium within vessels which requires a pressure difference between one part of the system and another
• a mechanism to maintain the mass flow movement in one direction like valves
• a means of controlling the flow of the transport medium to suite the changing needs of different parts of the organism
• a mechanism for the mass flow of water or gases like the intercostal muscles and diaphragm during breathing in mammals

Question 3

which circulatory system do mammals have?

Answer 3

• mammals have a closed double circulatory system in which blood is confined to vessels and passes twice through the heart for each complete circuit of the body since when blood is passes through the lungs its pressure is reduced
• blood is returned to the heart to boost its pressure before being circulated to the rest of the tissues
• substances are then delivered to the rest of the body quickly which is necessary as mammals have a high body temperature and a high rate of metabolism

Question 4

Why do large organisms have a transport system?

Answer 4

-organisms are evolved into large and more complex structures and the tissues and organs become more specialised and dependent upon one another

Question 5

Why is the final journey of substances to cells rapid?

Answer 5

-it takes place over a large surface area across a short distance and there is a steep diffusion gradient

Question 6

What does a transport system do?

Answer 6

-it takes materials from cells to exchange surfaces and to the environment

Question 7

how do animals create pressure differences between the transport system?

Answer 7

• animals use muscular contraction either of the body muscles or of a specialised pumping organ like the heart
• plants rely on natural passive processes like the evaporation of water

Question 8

what are the three types of vessels in the circulatory system?

Answer 8

• arteries
• veins
• capillaries

Question 9

Which factors decide if an organism has a specialised transport medium?

Answer 9

• the surface area to volume ratio

- how active the organism is